. >> a lot was said four years ago about joe biden's debate with sarah palin. now, he has known congressman ryan for quite some time. they have dealt together. how do you expect the tone to be different? >> well, remember, four years ago, biden had really one big challenge. he didn't want to make any major mistakes. but his only really great big challenge in that debate was sarah palin was this new figure, very controversial, had had some recent slip-ups. he had to not come across as condescending. he had to have an even performance, get through the night. this is going to be a very different night. as you said, the two men know each other, they both have very in-depth policy backgrounds. i think you'll see a lot more depth of policy knowledge exchanged, a lot more barbed attacks, and biden's going to have to go after ryan for those particular policies and talk a lot about his own expertise in not only budget matters but also foreign policy. i think you'll see a lot more depth in terms of the conversation on thursday than you did four years ago. >> carrie dan,